class Student {
    fullName: string;

    constructor(public firstName, public middleInitial, public lastName) {
        this.fullName = firstName + " " + middleInitial + " " + lastName;
    }
}

interface Person {
    firstName: string;
    lastName: string;
}

function greeter(person: Person) {
    return "Hello, " + person.firstName + " " + person.lastName;
}

let user = new Student("Jane", "M.", "User");

document.body.innerHTML = greeter(user);

let d :any;

function f1() {
    if (d==1){
        return "ok";
    }else {
        return true;
    }
}

let a:Document;